1. Field of the Invention
This invention relates generally to improved semiconductor power devices and more specifically to devices containing both FET and bipolar portions interconnected to share the current in a way that optimizes the capabilities of both portions.
2. Description of the Prior Art
Heretofore, known combinations of FET and bipolar devices have in the main comprised arrangements where one or more MOS devices were connected to control the base current of a bipolar device. Such arrangements were contrived both because the combination was susceptible to simple integration or merger and because it was difficult to produce high-current FET devices at high yield.
With the advent of practical high current FET devices, it is advantageous for some applications to eliminate the bipolar transistor altogether. In other applications, a parallel combination of FET and bipolar devices provides improved results. Such an arrangement is described in the related application cited hereinbefore and which is hereby expressly incorporated by reference for its inclusion of fabricational details. In that application, a preferred embodiment of the composite device included separate input terminals for the FET device and for the bipolar device; by appropriate sequencing of input signals during turn-off the advantage of the low "on" voltage of the bipolar device could be retained while largely obviating its potentially destructive latchback. The separate input terminals add complexity to both the drive circuitry for the device and its packaging.